372 XVII. scYTONEMACEiE (West). [Scytonema 



having parallel margins with long cells, others having firm irregular 

 margins with somewhat torulose trichomes, consisting of very short 

 transversely elliptic cells of irregular size. The latter filaments much 

 resemble the branches of a Stigonema. The sheaths of this plant are 

 altogether remarkable, being quite colourless, and often very irregular 

 in the margin ; wherever they come in contact with each other they 

 appear to coalesce, and this coalescence gives rise to a phenomenon 

 (viz. the apparent inclusion of two parallel trichomes in the same 

 sheath) which, so far as we are aware, has not been previously noticed 

 in this genus. The branches are also most peculiar, the majority being 

 solitary, and given off laterally from one cell of the primary filament 

 precisely as in Hapalosiphnn. Taking into consideration all these 

 points, there are still unmistakable characters which place the plant in 

 the genus Srytoitema. 



2. TOLYPOTHRIX Kiitz. (1843). 

 After examining the three following species, we cannot agree 

 with Bornet and Flahault in separating the genera Hassalia and 

 Tolypothrix. The former is said to be distinguished from the 

 latter by its fragile filaments and its terrestrial habit. The three 

 species referred to are all terrestiial as described for JIassallia, but 

 the sheaths (especially that of 1\ crassa) are very firm, persistent, 

 and flexile, agreeing with those of Tolypothrix. Under which 

 genus ought these species to be placed ? The terrestrial habit 

 points to JIassallia, the flexile and non-fragile filaments to 

 Tolypothrix. It appears to us that the only character left to 

 separate the two supposed genera is the fragility of the sheaths, 

 which in itself is certainly an insufiicient generic distinction. 



1. T. crassa W, et G. S. West in Journ. Bot. 1897, p. 267. 

 PuNGO Andongo. — Ad dextr. flum. Cuanza locis palustribus inter 



Lythraceas, etc. prope Candumba ; March 1857. No. 11. 



2. T. phyllopMla W. et G. S. West in Journ. Bot. 1897, p. 267. 

 GoLUNGO Alto. — Ad folia viva Rinorea: {AUodeio') spec, e Viola- 



cearum famiha, in sylvis densis de Alto Queta ; Dec. 1855 {Sine tnimero). 

 The nearest species to this is T. bi/s-^oidea (Hass. Brit. Freshw. 

 Alg. i. 233-4 ; ii- t. Ixvii. f. 5), from which it differs in its much 

 thicker colourless sheath, which is not fragile, and in the usually 

 longer cells. 



3. T. arenophila W. et G. S. West in Journ. Bot. 1897, p. 267. 

 PuNGO AxDONGO. — Ad terram arenoso-humosam in editissimisrupi- 



bus PrjBsidii Pedra Cazella, cum SchirjAtiche ik-licatisaiina ; Jan. 1857. 

 No. 151. 



4 T. limbata Thur. in Born, et Flah. in Ann. Sci. Nat. 7'" 

 serie, Bot. v. 124 (1887) ; W. et G. S. West, I.e. 



A smaller form with yellowish brown sheaths, which are often 

 somewhat rough on the exterior. 



M()S?!AMr.DES. — Cum OxcilUdoria tenui in umbrosis muscosis ad ripam 

 fluminis Bero, etiam in stagnis profundis post pluvias remauentibus 

 pelliculas liete virides natantes formans, prope Cavalheiros; Aug. 1859. 

 No. 191. 



